The present invention relates to a system and method of inspecting a selected part design from an inventory of computer-aided part designs for die compliance as to geometric characteristics of the part design with respect to die lock, draft, and sharp edge.
The number of design inspections performed on parts or workpieces increases each year as the supply of parts increase. In turn, the need for more effective design inspections also grows. More specifically, the need for a more efficient method of inspecting computer-aided part designs for die casting, injection molding, and stamping continues to increase, which increases part design productivity.
In the automotive industry, many parts are designed by using computer-aided software and hardware systems. For example, a system in which parts are created on a computer is called a computer aided design (CAD) system. A system in which parts may be manufactured by control of a computer is called a computer aided manufacturing (CAM) system. A CAD/CAM system aids the designer in several ways such as in developing the geometric detail required for the part which includes shape, dimensions, tolerance, etc. Alternatively, parts may be designed by other ways such as by machining which do not involve computer aided systems. However, without a CAD/CAM system, design and manufacturing costs and time typically are substantially higher.
Computer-aided part designs may or may not be evaluated prior to physically constructing the tool or the die thereof. In some situations, the dies of computer-aided part designs are directly constructed or xe2x80x9chand tooled.xe2x80x9d Then, after construction, the die is tested by actually attempting to manufacture the computer-aided part design. If no problems arise, then the part design is complete. However, if problems arise such as die lock, draft, or sharp edge, then further designing is necessary for the part design. In such situations, part designing may become very expensive and time consuming.
Also, computer-aided part designs may be checked manually for manufacturing or tooling feasibility and design efficiency, which may also result in very high costs. Typically, after the computer-aided part design is completed by a design engineer, a product engineer inspects the design for potential die lock, insufficient draft, and sharp edge. However, in most situations, the inspection involves only a manual or xe2x80x9ceyeballxe2x80x9d check. In fact, the only detailed inspection that is performed occurs when the manufacturer or supplier checks the part design for die lock, draft, and sharp edge by manual calculation methods. In some situations, a manual check is not sufficiently accurate in detecting die lock, draft and sharp edge. An insufficient inspection may result in manufacturing infeasibilities which consumes time and, in turn, leads to higher costs.
In many situations, the product engineer or manufacturer determines that the part design has die lock, insufficient draft, or a sharp edge. In this event, the design engineer is then notified that further design and modifications are required thereto, reducing design efficiency and productivity. Particularly, this increases the design time and labor costs, and decreases production rates and product quality rates. As an ultimate result, costs are increased.
Additionally, some CAD/CAM systems are provided with basic evaluations for computer-aided part designs. Typically, such basic evaluations include simple algorithms to check for basic compliance as to a single characteristic of the part design, such as draft characteristics. By only performing basic evaluations of the part design, as a result, insufficient evaluations occur more frequently than desired. Insufficient evaluations frequently lead to more time required for further designing.
Thus, what is needed is an improvement in the inspecting of computer-aided part designs for tool feasibility to increase part design efficiency and productivity.
Accordingly, it is an object of the present invention to provide an improved system and method of inspecting a selected part design from an inventory of computer-aided part designs in order to meet the demand for higher design efficiency which increases the productivity of part designs.
It is a further object of the present invention to provide an improved system and method of inspecting a computer-aided part design in order to lessen inaccurate inspections which lead to manufacturing infeasbilities.
A more specific object of this invention is a method of inspecting a selected part design from an inventory of computer-aided part designs for die compliance as to the part design""s geometric characteristics of die lock, draft, and sharp edge. The method involves selecting the part design to be inspected for die lock, draft, and sharp edge compliance so that geometric information for the selected part design is acquired and defining a die open direction for the selected part design based on the geometric information of the selected part design. After defining the die open direction, the method then involves evaluating the die lock and draft characteristics of the selected part design with respect to the defined die open direction. This is done to determine if the die will open in the direction defined. Then, the method involves evaluating the sharp edge characteristic of the part design irrespective of the defined die open direction. This is performed in order to determine the degree of edge sharpness in comparison to a predetermined geometric characteristic of edge sharpness for the selected part design.
Another specific object of this invention is a more specific method of inspecting a selected part design from an inventory of computer-aided part designs for die compliance as to the part design""s geometric characteristics of die lock, draft, and sharp edge. The method involves selecting the part design to be inspected for die lock, draft, and sharp edge compliance so that geometric information for the selected part design is acquired and defining a die open direction for the selected part design based on the geometric information of the selected part design. After defining the die open direction, the method includes selecting a die lock, a draft, or a sharp edge evaluation which is to be performed on the selected part design. If the die lock evaluation is selected, then the method involves determining whether the workpiece is complex.
If the workpiece is determined to be not complex, then the method involves casting evenly-spaced rays through the surfaces of the designed workpiece such that the casted rays are parallel to the defined die open direction and sorting the points of intersection for each ray. If any casted ray has greater than a threshold intersecting number, then the workpiece has die lock.
If the workpiece is determined to be complex, then the method involves defining a normal vector originating from a surface of the part design and casting a single ray from the origin of the normal vector such that the casted ray is parallel and in the same direction as the normal vector. Then, the method includes determining the number of intersections of the single casted ray and determining that the workpiece has die lock if the single casted ray is greater than a maximum intersection number.
If the draft evaluation is selected, then the method involves defining a normal vector for a surface and finding a first angle between the normal vector and the die open direction. If the difference between a reference angle and the first angle is found to be less than a minimum draft angle, then the method involves indicating that the surface has insufficient draft. If not, then the method includes indicating that the surface has sufficient draft.
If the sharp edge evaluation is selected, then the method involves determining a second angle between a pair of adjoining surfaces to define an edge and determining a supplementary angle of the second angle. If the supplementary angle is greater than a maximum sharp edge angle, then the method involves indicating that the edge has a sharp edge.
Another specific object of this invention is an inspection system of a selected part design from an inventory of computer-aided part designs for die compliance as to the part design""s geometric characteristics of die lock, draft, and sharp edge. The system includes a mechanism for selecting the part design to be inspected for die lock, draft, and sharp edge compliance such that geometric information for the selected part design is acquired. The system further includes a mechanism for defining a die open direction for the selected part design based on the geometric information of the selected part design. The system further includes a mechanism for evaluating the die lock and draft characteristics of the selected part design with respect to the defined die open direction to determine if the die will open in the direction defined. The system also includes a mechanism for evaluating the sharp edge characteristic of the part design irrespective of the defined die open direction to determine the degree of edge sharpness in comparison to a predetermined geometric characteristic of edge sharpness for the selected part design.